This invention relates generally to deployable truss beams, and more particularly to the apparatus and manner in which a three-dimensional, tetrahedron-based truss of square or rectangular section can be expanded and retracted in a continuous, stable, synchronous fashion in a variety of combinations and configurations to form a load-carrying beam or mast. Four longitudinal truss chords are formed by primary and secondary chord members, which can be formed by hinged, rigid, or flexible members. Chord members are connected by framesets comprised of truss diagonal members. Continuous, stable and synchronous motion while extending and retracting the truss is achieved by the use of uniquely incorporated orthogonal hinge joint fittings connecting the framesets and the chord members. The orthogonal hinge joint axes become orthogonal to each other at full extension of the truss and remain parallel at all times.
There have been many attempts to design, for various operating environments, a practical compact folding or flexing truss structure which can transition easily between the retracted and the useful extended state while exhibiting favorable characteristics of size/volume ratio, kinematic stability, simplicity and reliability, structural efficiency and weight, complexity, auxiliary mechanism requirements, manufacturing costs, speed of operation, and operating cost. Relatively few designs have appeared in the marketplace. Notable high-profile, and high-flying, examples are deployable trusses used in space missions such as for solar array deployment on NASA's International Space Station. Undesirable features of existing deployable trusses include complexity, inability to move in a coordinated and synchronous manner, requirements for a dedicated deployer and auxiliary mechanisms, and high cost.
Thus, what is needed is a deployable truss that achieves synchronous coordinated motion of all members while extending or retracting, is stable and self-forming and requires no dedicated auxiliary mechanisms and structures, and yet remains low in weight, complexity, and cost.